sound/firewire/lib.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * miscellaneous helper functions
   4  *
   5  * Copyright (c) Clemens Ladisch <clemens@ladisch.de>
   6  */
   7
   8 #include <linux/delay.h>
   9 #include <linux/device.h>
  10 #include <linux/firewire.h>
  11 #include <linux/module.h>
  12 #include <linux/slab.h>
  13 #include "lib.h"
  14
  15 #define ERROR_RETRY_DELAY_MS    20
  16
  17 /**
  18  * snd_fw_transaction - send a request and wait for its completion
  19  * @unit: the driver's unit on the target device
  20  * @tcode: the transaction code
  21  * @offset: the address in the target's address space
  22  * @buffer: input/output data
  23  * @length: length of @buffer
  24  * @flags: use %FW_FIXED_GENERATION and add the generation value to attempt the
  25  *         request only in that generation; use %FW_QUIET to suppress error
  26  *         messages
  27  *
  28  * Submits an asynchronous request to the target device, and waits for the
  29  * response.  The node ID and the current generation are derived from @unit.
  30  * On a bus reset or an error, the transaction is retried a few times.
  31  * Returns zero on success, or a negative error code.
  32  */
  33 int snd_fw_transaction(struct fw_unit *unit, int tcode,
  34                        u64 offset, void *buffer, size_t length,
  35                        unsigned int flags)
  36 {
  37         struct fw_device *device = fw_parent_device(unit);
  38         int generation, rcode, tries = 0;
  39
  40         generation = flags & FW_GENERATION_MASK;
  41         for (;;) {
  42                 if (!(flags & FW_FIXED_GENERATION)) {
  43                         generation = device->generation;
  44                         smp_rmb(); /* node_id vs. generation */
  45                 }
  46                 rcode = fw_run_transaction(device->card, tcode,
  47                                            device->node_id, generation,
  48                                            device->max_speed, offset,
  49                                            buffer, length);
  50
  51                 if (rcode == RCODE_COMPLETE)
  52                         return 0;
  53
  54                 if (rcode == RCODE_GENERATION && (flags & FW_FIXED_GENERATION))
  55                         return -EAGAIN;
  56
  57                 if (rcode_is_permanent_error(rcode) || ++tries >= 3) {
  58                         if (!(flags & FW_QUIET))
  59                                 dev_err(&unit->device,
  60                                         "transaction failed: %s\n",
  61                                         fw_rcode_string(rcode));
  62                         return -EIO;
  63                 }
  64
  65                 msleep(ERROR_RETRY_DELAY_MS);
  66         }
  67 }
  68 EXPORT_SYMBOL(snd_fw_transaction);
  69
  70 #define PROBE_DELAY_MS          (2 * MSEC_PER_SEC)
  71
  72 /**
  73  * snd_fw_schedule_registration - schedule work for sound card registration
  74  * @unit: an instance for unit on IEEE 1394 bus
  75  * @dwork: delayed work with callback function
  76  *
  77  * This function is not designed for general purposes. When new unit is
  78  * connected to IEEE 1394 bus, the bus is under bus-reset state because of
  79  * topological change. In this state, units tend to fail both of asynchronous
  80  * and isochronous communication. To avoid this problem, this function is used
  81  * to postpone sound card registration after the state. The callers must
  82  * set up instance of delayed work in advance.
  83  */
  84 void snd_fw_schedule_registration(struct fw_unit *unit,
  85                                   struct delayed_work *dwork)
  86 {
  87         u64 now, delay;
  88
  89         now = get_jiffies_64();
  90         delay = fw_parent_device(unit)->card->reset_jiffies
  91                                         + msecs_to_jiffies(PROBE_DELAY_MS);
  92
  93         if (time_after64(delay, now))
  94                 delay -= now;
  95         else
  96                 delay = 0;
  97
  98         mod_delayed_work(system_wq, dwork, delay);
  99 }
 100 EXPORT_SYMBOL(snd_fw_schedule_registration);
 101
 102 MODULE_DESCRIPTION("FireWire audio helper functions");
 103 MODULE_AUTHOR("Clemens Ladisch <clemens@ladisch.de>");
 104 MODULE_LICENSE("GPL v2");